Phosphodiesterase 10A is an enzyme from the phosphodiesterases family with specific localisation of expression predominantly in the brain in striatum, the part of basal ganglia having various functions involved in control of motor movement, cognitive processes, emotions and learning. On the basis of presently available evidence this enzyme is believed to play a role in the regulation of response to external stimuli and in some aspects of cognitive functions. The present state of the knowledge of PDE10 activity allows to believe that compounds exhibiting the ability of PDE10A inhibition might have advantageous effects in dysfunction of basal ganglia system, including psychotic, neurological and cognitive functions disorders, such as for example psychosis, including psychosis in schizophrenia, Huntington's disease, Parkinson's disease, addictions and obsessive-compulsive disorders.
There are also reports of enhanced PDE10 expression in colorectal cancer cells. Also described is proapoptotic activity of PDE10 inhibitors against colorectal tumour-derived cell lines characterized by enhanced expression of TCF/Lef promotor-dependent genes. This allows to believe that compounds exhibiting the ability of PDE10A inhibition might have advantageous effects in the treatment of colon and rectal cancers.
In WO2013/003298 there are disclosed as phosphodiesterase 10A inhibitors the compounds based on imidazo[1,2-a]pyridine core of the following general formula, wherein X represents N or CR7, wherein R7 can be a bicyclic heteroaromatic group containing 2 to 4 nitrogen atoms.

In U.S. Pat. No. 8,410,117 there are disclosed as phosphodiesterase 10A inhibitors the compounds based on carbamoyl-substituted imidazo[1,2-a]pyridine core of the following formula

Various PDE10A inhibitors are disclosed in the art. Some of them are in the phase of clinical trials. However, none of PDE10A inhibitors has been introduced as a medicament into clinical practice.
The need still exists of search new PDE10A inhibitors of potential utility in the treatment of neurological and psychotic diseases and disorders. Such compounds are provided by the present invention.